As credit and debit cards gradually take over the sphere of purchasing, money becomes less and less a physical thing. Whereas a decade ago satirists were drawing images of moguls swimming in a sea of bills, this satire is shifting to illustrate these same moguls now depositing checks with too many zeroes into overseas bank accounts. Even in our personal lives, carrying cash rarely has many applications—cards are accepted everywhere, and even when they aren’t there’s almost always an ATM within reach. But as we become more disconnected from our understanding of what is actually signified by our bank balance, by our available funds, it becomes important to reminisce on what the dollar physically is.

American currency has undergone a few major shifts. In the last decade, we’ve seen changes to the $5, $10 and $20 bills up to $100 bills, shifting from using the classic $1 style to a purplish numbering and much larger numerals—in many instances as an attempt to keep up with current counterfeiting technology. Printed money is painstakingly constructed, both for design and in an effort to make it harder to duplicate the process. This effort starts with engraving the plates, which are used for the intaglio printing onto the linen-cotton composite bills. Each bill is stamped with a force of around 10,000 psi, which is responsible for generating the raised texture of the ink.

Classically, what we understand as dollar bills used to be referred to as bank notes. They originated as a promissory note from banks to pay the bearer in coins, but as currencies shifted and inflation began working on a global scale, they soon became currency in their own right. This is where the shift from bills being produced by the banks themselves to being produced by, in many countries, a nationally appointed ‘central bank’ took place, gradually accepting them as indicators of a nation’s currency. Currently, these bills are printed at the Bureau of Engraving and Printing.

Coins go back much further, intended as a form of currency with a physical form that directly correlated to its value. This value of coins is known as their ‘melt value’, how much the coin is actually worth from a use standpoint when the metal is melted down and used for practical purposes. As inflation continued over centuries, this gradually became more and more obsolete, but coins maintain this intrinsic quality regardless.

It’s easy to lose track of spending when you aren’t handing over the coins and bills yourself. Without something physical and tangible to associate your wages and payments with, it becomes much easier to give. Keep in mind just what you’re paying with every time you use your card, regardless of where that actual, physical money may be.